Unless otherwise indicated herein, the description provided in this section is not itself prior art to the claims and is not admitted to be prior art by inclusion in this section.
A cellular wireless network may include a number of base stations that radiate to define wireless coverage areas, such as cells and cell sectors, in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wireless equipped communication devices, can operate. In turn, each base station may be coupled with network infrastructure that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or a packet-switched network such as the Internet for instance. With this arrangement, a UE within coverage of the network may engage in air interface communication with a base station and may thereby communicate via the base station with various remote network entities or with other UEs.
In an example arrangement, the network infrastructure may include one or more packet data network gateways (PGWs) or similar components that provide connectivity with a packet-switched network so as to support general packet-data communications, such as general web browsing, file transfer, and the like, and/or packet-based real-time media communications such as voice over Internet Protocol (VoIP) and streaming media for instance.
A representative PGW may sit as a node on a wireless service provider's private packet-switched network and may thus provide connectivity with various application servers and other entities on that private network, and with other such entities accessible through a connection between the service provider's network and one or more other networks such as the public Internet. By way of example, such a PGW may provide connectivity with an Internet Multimedia Subsystem (IMS) platform or other session server that supports VoIP calling and/or other such media services.
When a UE first enters into the coverage of a cellular wireless network, the UE engages in a process of registering or “attaching” with the network, which may trigger setup of various communication channels for the UE and/or reservation of various communication resources for the UE. For instance, upon first detecting coverage of a base station, the UE may transmit an attach request message to the base station, which the base station may forward to a network controller such as a mobility management entity (MME). Upon authenticating and authorizing the UE, the network controller may then engage in further signaling with the base station and with a serving gateway (SGW), which may in turn engage in signaling with a PGW, ultimately resulting in setup of one or more bearer connections or “bearers” each extending, via the base station, between the UE and the PGW, through which the UE can then engage in packet-data communication via the PGW.
Each bearer established for a UE may define a logical communication tunnel that includes a radio bearer portion extending between the UE and the base station, and an access bearer portion extending between the base station and the PGW via the SGW. Further, each bearer may have a designated quality of service (QoS) level, which may dictate how the packet data transmission along the bearer is handled by the network. For instance, a bearer could have a relatively high QoS level, according to which network nodes (such as the base station, SGW, and various routers) along the bearer path could be set to prioritize routing of data on the bearer over routing of data on other bearers, perhaps to guarantee a particular minimum bit rate, a particular maximum level of packet delay, and/or a particular maximum level of data loss. Alternatively, a bearer could have a relatively low QoS level, such as a “best efforts” service level, according to which nodes along the bearer path would simply do their best to route data of the bearer, subject to higher priority handling of other bearer traffic.
In practice, a network such as this may initially establish for a UE one or more default bearers to enable the UE to engage in certain basic communications, with each default bearer having a respective QoS level. By way of example, the network may initially establish for the UE a default Internet bearer with a best-efforts QoS level, for use by the UE to engage in general Internet communication such as web browsing, e-mail messaging, and the like. Further, as the UE is served by the network, the network may establish for the UE additional bearers as needed. For instance, the network may establish for the UE a default IMS signaling bearer for use by the UE to engage in session setup signaling with the IMS to facilitate setup of packet-based real-time media sessions. And if the UE engages in signaling over the default IMS signaling bearer to setup a packet-based real-time media session, the network may establish for the UE a dedicated IMS bearer for carrying media content of the session.
Once the UE has completed the process of registering or attaching with the network, the UE may operate in an idle mode, meaning that the UE does not currently have assigned traffic channel resources on which to engage in UE-specific data communication. In the idle mode, the UE may periodically read a downlink control channel to receive overhead information from the network and to check for any paging messages destined to the UE. And when the network has packet data for transmission to the UE, the network may page the UE to then facilitate assigning traffic channel resources to the UE.
By way of example, in a Long-Term Evolution (LTE) system, a UE may operate in a discontinuous idle mode in which the UE operates with low power but periodically wakes up to check a downlink air interface control channel for a paging message. In particular, the LTE downlink defines frames of 10 milliseconds each divided into subframes of 1 millisecond each, and the UE may be configured to periodically check one or more “paging occasions” of the control channel in a particular frame and particular subframe(s) in search of a paging indicator. Upon finding such a paging indicator, the UE may then check a corresponding downlink shared channel space to see if there is a paging message for the UE. To transmit a paging message to the UE, a base station may thus set the paging indicator in a paging occasion that the UE is set to check and may include in the corresponding downlink shared channel space the paging message for the UE.
In practice, the UE would hash onto a particular paging occasion, based on an algorithm keyed to the UE's identifier and perhaps one or more other parameters specified in a system message. Further, the base station would apply the same hashing algorithm to determine the particular paging occasion in which the UE will expect any paging messages and the base station may transmit any paging message to the UE in that particular paging occasion.
For instance, in an LTE system, each paging frame may have a system frame number that ranges from 0 to 1023 and periodically repeats. In such a system, the UE may determine which paging frames to monitor using an algorithm keyed to the UE's International Mobile Subscriber Identity (IMSI), a unique number used to identify the UE. As an example, the algorithm may specify that, based on a UE's IMSI, the UE may be configured to check each paging frame where the system frame number is equal to 75, 203, 331, 459, 587, 715, 843, or 971. Note that this example amounts to checking a paging frame every 128 system frames (i.e., every 1.28 seconds). Furthermore, the UE may determine which subframe(s) of those paging frames to monitor using the algorithm. For instance, the algorithm may also indicate that the UE should monitor the tenth (i.e., last) subframe of each of those paging frames. Similarly, the base station may apply the same algorithm and determine that the base station should transmit any paging messages destined for the UE in the tenth subframe of the above-referenced paging frames. In this manner, the base station may transmit paging messages to the UE in paging occasions in which the UE is configured to monitor for paging messages.